Furnace arch



M. BAENTER FURNACE ARCH Filed Feb. 20, 1926 pasarse oa. 4, 1927.

UNITED STATES Pari-:NT OFFICE. l

MILFORD BAINTER, 0F COLUMBUS, OIIIO,v ASSIGNOR 'IO S. OBRMAYER COMPANY,OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

FUR-NACE ARCH.

Application led February 20, 1926. Serial No. 89,615.

The object which I have in view is the provision of a practical furnacearch formed monolithically of plastic refractory material and which Willbe durable and not collapse.

The present practice is to build furnace arches of fire brick or ofspecially designed refractory tile. This method of construction isexpensive, owing to the cost of material, and the time and skilled laborrequired in its erection. Furthermore the joints between the units tendto open due to eXpansionv and contraction inthepresence of varyingtemperatures, resulting in spaivling and, frequently, in the collapse orfailure of the arch.

Monolithic arches when constructed in accordance with my invention arepreferable to the arches above referred to lowing to the lower cost ofmaterials, the employment of unskilled labor, the shorter time requiredfor erection, and the absence of'joints.

Furnace arches constructed of plastic refractory material have hithertonot been generally recognized inthe art as a success, owing to theirtendency to collapse. A leading cause of this Weakness is thedifficulty, hitherto unsurmountable, in properly and uniformlyvitrifying the mass of plastic material, and thus the unitary structurelacked in strength and cohesion, portions tending to crumble underservice conditions.

In a monolithic furnace arch constructed in accordance with my inventiont-he entire mass of plastic refractories may be properly and uniformlyvitrified, thus preventing the incorporation in the mass of portionswhich remain more or less plastic or merely dried out Without propervitrification. I obtain this very important result by subjecting` theinterior of the mass to the direct influence of the vitrifying heat.This I effeet by embedding in the mass of the plastic material aplurality of tubes Whose ends are open to the entrance of the vitrifyingheat currents which thus are caused to travel through the mass.

To strengthen the monolithic arch during t-he drying and vitrifyingperiod I embed in the material thereof metal reinforcement positioned toassume the tension strains which the refractory material is less able toresist, and for this purpose I employ the tubes above referred to, thesame being so disposed transversely of the lfurnace to Yflinction asthetension chord of the furnace arch,

and in case of curved arches being curved to follow the arc of the archand in the case of flat arches being straight. These metal arches areplacedat suitable intervals depending on the strains they are to assume.y

These arch-tubes are preferably placed in position before theplasticmaterial is filled in on the form, the ends of the tubes being supportedand closed by abutment blocks mounted on the form and composed ofreadily combustible material, preferably Wood. lVhen the plasticmaterial has been filled in and properly rammed a fire is started in thefurnace which burns out the abutment blocks', leaving the arch tubesembedded in the plastic material with their ends in open communicationwith the recesses in the under surface of the arch'left by the conisumpt-ion of the abutment blocks.

I further combine With the arch, recuperator means which preheat airtaken from Without the furnace and deliver it'to the secondarycombustion chamber vin the rear of the arch, thus assisting the completecombustion of the gases released from t-he fuel bed on the furnacegrates.

The recuperator means comprise metal tubes embedded longitudinally inthe mate riall of the arch above the arch tubes having their ends att-he front of the arch open to atmosphere for the entrance of the airWhile their rear ends open into the furnace in the rear ofthe arch. f

These reverberatory pipes also act as longitudinal enforcement of thearch, and are therefore placed vadjacent tothe lower surface of thearch.

Other novel features of construction, and also of arrangement of partswill appear from the following description.

In the accompanying drawings, wherein I have illustrated the bestembodiment of the principles of my invention now known to me, Fig. 1 isa'transverse vertical section of a furnace arch, the Wooden form beingshown in place but the abutment block being removed at one end of thearch tube; Fig. 2 is a longitudinal vertical section of the same, andFig. 3 is an enlarged perspective of the preferred form of abutmentblocks.

Referringto the drawings 1 represents the side walls of the furnacewhich may be built of brick', tile, plastic refractories or othersuitable material, and which are provided on the inside with theshoulders or ledges 2 which form the base or abutment of the furnacearch. 3 represents the lcross girders, usually steel I-beams which aresupported at their ends on the walls 1. The body of the furnace arch iscomprised of the plastic refractory material as indicated at 5, thesamebeing filled; in and` tightly rammed on the wooden form- 6 which iserected in the lire chamber of the furnace.

7 represents the top covering or skin of brickV work which is usuallysuperimposed on the monolithic archl proper.

8 represents a plurality of upwardly arched metal tubes which arepositioned transversely ofthe furnace and in spaced relation to eachyother, Vthe tubes being of suc-hl'ength that their ends are spacedslightly inwai-'dly from the sidewalls 1, andbeing supported and theirends closed by the abutment blocks Q'which are mounted in position onthe form 6. The blocks arepreferably of woodl having nailed to theirinner faces the pieces of board 1:0 having not'chll cut in theirl upper.ends. Thus the ends of the tubes 8 rest in the notches 11 and abutaga-inst and are closed byA the blocksl 9; The tubes are also held in.position by the wire hangers 12 which are looped about the tubes andalso about rods llfextendi-n-g longitudinally of the furnace a-ndsupported in place bythe girders 3. t

14 represents a plurality of parallel tubes disposed longitudinally ofthe furnace and embedded in` they refractory materiali 5 slightly abovethe archl tubes.- 8. The grouping of the tubes 14 follows the arcy ofthe tubes 8 soas to be equally distant therefrom. Thus the tubes 14cooperate with the tubes 8 to assume the Itension strains in the arch,which strains the refractory material is less able to safely assume.

The front ends of the tubes. 14 are turned upwardly as at 15, and areopen throughA the brick skin 7, so as to draw in atmospheric air or thepipes 14 may be open through the front of the arch. or otherwisecommunicating with atmosphere atthe front ofthe furnace. The rear endslof the tubes Open through the arch into the secondary combustion chamber14au in the rear of the furnace arch;

Thus air is drawn rearwardly through the tubes 14, is heat-ed in transitajnd delivered. in a heated state to the secondary combustion chamber.

fThus l provide a superheater for the air which induces completecombustion of the furnace gases..

16 represents a vertical wall at the rear end of the arch, which isfrequently pro.-

vided to close the front of a vertical boiler. Such wall may beconstructed of plastic refractories and may be conveniently reinforcedby vertical tubes 17 whose lower ends are connected to the tubes 14 butwhose upper ends vare closed to prevent the upward escape ofthesuperheated air. f

The tubes 14 are properly held in position the filling in of the plasticmaterial of the arch, as by the wire hangers 18 entending up to the rods13.

In constructing the arch, Iiirst install the wooden form 6l with theopposed pairs of blocks 9 mounted thereon. The arch tubes 8 andthe-recuperator tubes 14 are then put in place and properly stayedagainst accidental,displacement. The plastic material 5 which is tocomprise the body of the arch is filled in on the form `and firmlyrammed with the pipes 8 The material is also filled in and rammed aboutand' over the girders 3 and the rods 13 and usually given an arched topsurface which is preferably subsequently provided with an outer skin orprotective surf-ace 7 of brick.

After the material 5 has dried sufficiently a` fire is built andmaintained in the furnace. The fire quickly burns out the combustibleblocks 9, leaving a void orrecess 19, shown at the right in Fig. 1, inthe under side of the arch into which recess the end of thecorresponding pipecommunicates, so

that the tubes form arched passageways in the furnace arch whichcommunicate at each end through the recesses 19 with the interior of thefurnace. These passages are of great value as the hot gases from thefire are thus caused to travel through said tubes thereby subjecting theinterior portions of the plastic mass to a greater and more'uniformly'distributed heating action whichresults in the uniform vitrificationofthe entire plasti-c mass.

It is evident that the pipes also function during the normal operationof the furnace means for conducting the furnace gases from one side ofthe furnace to the other from an area ofy greater heat to oneof lessheat, thus equalizing the temperature of the furnace and improvingcombustion.

It is further evident that the air is drawn rearwardly through the tubes14, becoming heater. as it travels through the arch and is delivered ina superheated state to the secondary combustion chamber.

In furnaces where a vertical wall, such as 16, rises at the rear of thearch a gas pocket or dead space is formed at the rear of the wall whichit is difiicult to heat. The delivery of the superheated air from thepipes 14 to the lower portion of such space results in. intensecombustion of the furnace gases in this space, thus abolishing the deadspace.

My improved arch may be erected in much and emi e'dded therein..

lll)

lill) much cheaper than fire brick or refractory tile.

The upkeep and'maintenance of my improved arch is also much less, as incase of such necessity it may be readily repaired by ramming in a patchof the saine material as that of whichvit is made. yRepairs are howevernot frequently required as in brick or tile arches, as my archismonolithic in character and thus presents no joints. There is thus noloss of heat from leakage through the arch.

The recuperator tubes have also the function of keeping down thetemperature of the arch, thus preventing the possibility of 1; burningout the arch, avfrequent occurrence in brick or tile arches.V r Y Theintroduction of superheated air into the secondary combustion chamberincreases the degree of combustion of the products of the fuelcombustiony on `Jthe furnace grate bars, thus effecting fuel economy andimproving the furnace efficiency.

As the refractory material for the construction of my improved arch, Ilprefer to employ a plastic composition formed of blended clays, whichhave been weathered for a period. of from twelve to eighteen months toimprove their plasticity and reduce shrinkage, mixed with calcined flintmaterial which is of the consistency to pass through a screen havingfour wires to the inch, employing` the coarse and the fines of theflint. To this'may be added a small quantity of silica gannister runningabout 98% silica. In mixing up this composition I employ about 27% ofthe clays, 68% of the flint and about 5% of the silica gannister.

lhat I desire to claim is l. A monolithic furnace-arch constructed ofplastic refractory material and having 1 embedded therein transverselydisposed metal tubes, each tube having its two ends in opencommunication with the interior of Vthe combustion chamber of thefurnace through openings in the material of the arch.

2. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely `disposed metal tubes each tubehaving its two ends in open communication with the interior of thecombustion chamber of the furnace through openings in the material ofthe arch, said tubes being curved to conform to the curvature of thearch.

3. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely disposed tubes each tube havingboth its ends in open communication with'the interior of the furnace,said tubes being positioned to assume the tension strains.

4. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely Vdisposed tubes each tubehaving both its ends in open communication with the interior of thefurnace, said tubes following` the contour of the arch.

5. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely disposed tubes each tubehavingboth its ends in open communicationwith the interior of the furnace,said tubes following the contour of the arch and'being positioned toassume the tension strains. l i

6. A monolithic.furnaceearch constructed of plastic refractory materialand having embedded therein l transversely disposed tubes conforminglongitudinally to the contour of the arch, the ends of each of saidtubesbeing open to the interior of the furnace and other tubes disposedlongitudinally of the arch.

7. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely .disposed tubes conformingtothe contour of the arch, the ends of each of said tubes being open tothe interior of the furnace and other tubes disposed longitudinally ofthe arch, said second named tubes being mutually disposed to conform tothe curvature of the arch.

8. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely disposed tubes conforming tothe contour of the arch, the ends of each of said tubes being open tothe interior of the furnace and other tubes disposed longitudinally ofthe arch, all said tubes being positioned to assume tension strains.

9.' A monolithic furnace-arch constructed of plastic l refractorymaterial and havingr embedded therein transversely dispose tubesconforming to the contour of the arch, the ends of each of said tubesbeing open to the interior of the furnace and other tubes disposedlongitudinally of the arch, said second named tubes being groupedtoconform to the contour of the arch, all 'said tubes being'positioned toassume tension strains.

10. A monolithic furnace-arch constructed of plastic refractory materialand having embedded therein transversely disposed tubes conforming tothe contour of the arch, the ends of each of saidtubes being open to theinterior of the furnace and other tubes disposed longitudinally of thearch, said second named tubes being grouped to conform to the curvatureof the arch, said second named tubes also having their front ends lilin" cli 11. A monolithicfurnacesarch constructedy of plastic refractorymaterial and provided with transverse passages therethrough each having`their ends communicating with the interior of the furnace.

12. A monolithic:furnacearch constructed of plastic refractory materialland provi-ded With transverse passages therethrough each having theirends communicating with the interior of'the furnace, said passagesconforming to the contour ofthe arch.

13. A monolithic furnace-arch`constructed of plastic 'refractorymaterial and provided with transversely'dis` posed passages each havingtheir ends communicating 'with the interior of the furnace -andlongitudinally disposed passages having their front ends communicating'with atmosphere and their rear ends communicating Withthe secondarycombustion chamber. i

14. A monolithic furnace-'arch constructed of plastic refractorymaterial and provided with transversely disposed passages each havingtheir -ends communicating vvith the interior of the furnace andlongitudinally disposed passages having their front ends communicating'with atmosphere and their 'rear ends communicating with the secondarycombustion chamber, said first mentioned passages conforminglongitudinally to the contour of the arch and said secondmentionedpassages being grouped to conform to the contour of the arch.

v15. A monolithic furnace-arch constructed of plastic material andhaving embedded in the material thereof a plurality of metal tubesdisposed longitudinally of the arch, the tubes being supported in placeby the material of the arch and having their front ends open toatmosphere and their rear ends open to the secondary combustion chamberof the furnace, and saidtubes being positioned to assume the tensionstrains.

16. A monolithic furnace-arch constructed of plastic material an-dhaving embedded in the material thereof a plurality of metal tubesdisposed longitudinally of the arch, the tubes being supported in vplacebythe material of the arch and having their front ends open toatmosphere and their rear endsopen to thesecondary combustion chamber ofthe furnace, and said tubes being mutually disposed to conform to thetransverse contour of the arch.

Signed at Columbus, Ohio, this'lth day of February, 1926. p p

MILFORD BAINTER.

